Regensburg 2007 – scientific programme
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DY: Fachverband Dynamik und Statistische Physik
DY 3: Critical phenomena and phase transitions
DY 3.1: Talk
Monday, March 26, 2007, 12:00–12:15, H2
Tricritical dynamix at the demixing-superfluid transition in 3He-4He mixtures — •Reinhard Folk1 and Günter Moser2 — 1Institute fot theoretical Physics, University of Linz, Linz Austria — 2Department for Material Sciences, University of Salzburg, Salzburg, Austria
We calculate in two loop order the dynamical critical behavior at the tricritical point occuring in 3He-4He mixtures. Model F′ introduced by Siggia and Nelson [Phys. Rev. B 15, 1427 (1977)] - already problematic in one loop order - is shown to lead to a divergence of the mass diffusion D in contradiction to experiments. Within the complex symmetric version this model (model E⋆′) the dynamical critical exponents of the kinetic coefficients can be calculated exactly leading to a mass diffusion going to zero at the tricitical point as D(tX)∼ tX1/2 (tX the relative temperature distance at constant concentration) and the thermal diffusion ratio kT∼ tX−1 diverges proportional to the concentration susceptibility in the experimental region.
Supported by the Austrian Fonds zur Förderung der wissenschaftlichen Forschung, project No P18592